Plant Doctor Archive

 CAN you tell me what is causing the leaves on my giant maidenhair fern to turn brown? It is growing in a draft-free area with plenty of light. It grows well, but after the new leaves have been out for a while the tips turn brown.

  TIP burn on indoor plants is often a sign that all is not well with the roots. Too much water in the mix, or too little, or too much fertiliser can all cause these symptoms.

But with maidenhair ferns it is often a sign the mix is becoming too acidic. Unlike most ferns, they seem to prefer relatively neutral or even slightly alkaline soil pH. Most potting mixes tend to become more acidic with age and so repotting your fern into fresh mix may solve the problem.

Some gardeners report that watering maidenhair ferns with water eggs have been boiled in, or adding some broken eggshells to the potting mix, or simply having a few shells from the beach lying on top of the mix contribute to healthier foliage. And it makes sense, as calcium, which is found in shells, is the main element lacking in acidic soils.

Another cause for tip burn in maidenhairs is low humidity. Air conditioners and heaters can cause the surrounding air to be too dry. Depending on your house design, the humidity in a well-lit room can be very low. A good way to raise humidity around the plant is to sit the pot on a saucer filled with pebbles. Keep the pebbles moist but ensure the bottom of the pot is not in water. This will raise the humidity around the plant and should help reduce tip burn.

Weekend Gardener, Issue 207, 2006, Page 41

• The views expressed here are not necessarily those of the RNZIH
• Content or advice may be out-of-date.